Okay, let's tackle this question about the most common cause of epiphora in newborns. First, I need to recall what epiphora means. Epiphora is excessive tearing, right? So in newborns, why would they have too much tearing?

The options weren't provided, but the correct answer is probably a common condition in infants. Let's think about possible causes. Newborns can have blocked tear ducts because the nasolacrimal duct hasn't fully developed yet. That's a common issue. Other possibilities might include congenital abnormalities like dacryostenosis, or maybe something like conjunctivitis, but that's more about infection. Wait, dacryostenosis is another term for a blocked tear duct. So maybe that's the main cause.

Why would a blocked tear duct be the most common? Because in newborns, the nasolacrimal duct can be obstructed by a membrane at the distal end, called Hasner's valve. If that's not open, tears can't drain properly, leading to epiphora. Also, sometimes the duct hasn't developed fully yet, so it's just a developmental issue.

Other options might include things like corneal irritation or other infections. But those are less common. For example, if a baby has an infection from maternal bacteria during birth, like gonococcal or chlamydial conjunctivitis, that would cause redness and discharge, but maybe not the most common cause. Epiphora in newborns is usually due to a physical blockage rather than infection.

So the core concept here is the anatomical obstruction in the nasolacrimal duct. The correct answer would be congenital nasolacrimal duct obstruction or dacryostenosis. The other options like conjunctivitis, corneal ulcers, or eyelid malpositions are less likely. The clinical pearl is that most cases resolve spontaneously as the duct develops, but if not, probing might be needed later.

**Core Concept**
Epiphora in newborns is typically caused by anatomical obstruction of the nasolacrimal duct. The most common etiology is **congenital nasolacrimal duct obstruction (dacryostenosis)**, resulting from a persistent membrane at Hasner’s valve or underdeveloped duct.

**Why the Correct Answer is Right**
Congenital nasolacrimal duct obstruction occurs in 5–10% of newborns due to a failure of the distal nasolacrimal duct to open at Hasner’s valve. This prevents tear drainage, leading to excessive tearing (epiphora) and mucous discharge. The condition often resolves spontaneously within the first year as the duct matures or is cleared by probing.

**Why Each Wrong Option is Incorrect**
**Option A:** *Neonatal conjunctivitis* causes redness, chemosis, and purulent discharge but not primary epiphora.
**Option B:** *Corneal ulcers* are rare in neonates and present with pain, photophobia, and corneal opacity.
**Option C:** *Ectropion or entropion* may cause irritation but do not typically result in epiphora.

**Clinical Pearl / High-Yield Fact**
Congenital nasolacrimal duct obstruction is the most common cause of neonatal epiphora. Conservative management (lacrimal

✓ Correct Answer: B. Non-canalisation of nasolacrimal duct